A fascinating announcement this week from plant scientists at Purdue University in Indiana.

A reseach team led by Robert Pruitt has discovered a plant that ignored a mutation in its own DNA and somehow reached back to its ancestors to provide the correct genetic instructions for its offspring. [News release]

PRUITT: "So what we've discovered in the lab is that in some situations in arabidopsis, uh plants can inherit genetic information that was absent from their parents but was present in their grandparents or their great grandparents. So it's a new, sort of a new paradigm for genetics, uh, something completely different than anything we've seen before."

Arabidopsis is a mustard plant commonly used by scientists to study genetics. Dr. Pruitt and his colleagues studied arabidopsis plants that had a mutation which they should have passed on to the next generation.

PRUITT: "We can show that in fact those plants had inherited a normal copy of that particular gene, which wasn't present in their parents but which they must have inherited from an earlier ancestor."

Purdue's Robert Pruitt says this startling discovery, which is not fully understood, seems to disregard long-held understandings of genetics.

PRUITT: "I think the other thing is that it implies that these organisims can modify their genomes in a new way that we don't understand. And if we can understand that process, it opens up the possiblity of exploiting it in order to modify the genome in ways that we want to , to basically fix genetic defects, do gene therapy, that sort of thing."

Obviously, though, this discovery is still a long way from any possible application in treating diseases in plants or animals.

Astronomers have announced that for the first time, they've detected the light of two planets hundreds of light years away. The scientists say the development paves the way for the discovery of earth-like planets outside our solar system. VOA's Jessica Berman reports.

BERMAN: Since 1995, astronomers have been able to detect planets beyond our solar system through indirect means, such as the wobble that the planets' gravity exerts on nearby stars.

Scientists detected some 130 extrasolar planets this way. But now, with the development of more powerful telescopes, scientists are able to see the planets directly.

This week, two of those planets showed themselves to two independent teams of astronomers using instruments aboard the Spitzer Space Telescope, funded by the U.S. space agency NASA. Using two different instruments aboard the infrared telescope, the scientists picked up the light of the two planets on the edge of the galaxy. One of the planets is 140 light years from Earth and the other one is five-hundred light years. [News release]

David Charbonneau of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts headed one of the teams. Dr. Charbonneau says the planets have been difficult to see in visible light because they are outshown by their stars, which are ten-thousand times brighter. He says viewing the solar systems through the red tones of the infrared spectrum reduces the glare.

CHARBONNEAU: "If we put on our infrared goggles with the Spitzer Space Telescope, then suddenly the planet brightens up, and the contrast ratio, the difference in light between the star and planet is much, much more favorable, and we are to isolate that light from the planet directly and study it."

BERMAN: The planets can be seen during their solar orbits. When passing across the front of the sun, each planet causes its sun it to dim slightly. The solar system also dims when the planets disappear behind the back of the stars. By observing this secondary phase, or eclipse, through the infrared spectrum, astronomers are able to tease out the faint planetary light against the brightness of the stars.

Mr. Charbonneau believes the discoveries will be the first of many direct planetary sightings outside our solar system.

CHARBONNEAU: "Spitzer has allowed us to directly detect the light from planets orbiting other stars, not once, but twice. Two separate planets, you know, you have two separate teams. And they even used two different instruments on the Spitzer telescope. And both the detections are very robust, they're very secure. So, the excitement is that Spitzer should be able to do this many more times in the next few years."

BERMAN: The planets are what astronomers call "hot Jupiters," that is they are large, fluffy gas planets like the planet Jupiter in our solar system. Because the extrasolar planets are twenty times closer to their suns than earth is to its star, scientists estimate the temperature on the planets is probably around 850 degrees celsius.

Now that they're able to see distant planets beyond our solar system, astronomers hope to learn about the temperatures, atmospheres and orbits of many planets hundreds of light years away. In addition to gaseous planets, scientists look forward to discovering rocky planets like earth and the possibility of life forms.

BOSS: "I think these discoveries today have taken us a major step along that way. These truly are epochal discoveries, and we're well along the way toward establishing astrobiology as a new discipline."

BERMAN: The astronomers published their discoveries of the two extrasolar planets in the journals Nature and The Astrophysical Journal.

CHIMES: Time again for Our World's Website of the Week. It's a kind of time machine that provides an Internet window -- make that 10 million windows -- on the past.

LAMOLINARA: "American Memory is a website that contains digitized materials from the Library of Congress and also some other institutions, and currently it has more than 10 million items."

Guy Lamolinara is a spokesman for the Library of Congress, which has the world's largest collection of books, manuscripts, maps, film, audio recordings and so on. But until 1990 you normally had to visit the library here in Washington to use that material. Fifteen years ago, the Library of Congress began digitizing some of its materials. At first the plan was to distribute CD-ROMs to selected libraries. But when the Internet began to take off, around a decade ago, they saw that as the way to make all this material available, with an emphasis on items unique to the Library of Congress.

LAMOLINARA: "You're going to find millions and millions of items, most of them non-book items. For example, you'll see presidential presidential papers. We have all the papers of Lincoln, Jefferson, and George Washington available on-line. You'll see many, many things relating to the Civil War, such as Matthew Brady's Civil War photographs. We have a lot of collections relating to the Civil Rights movement and also relating to the struggle for women's suffrage."

The American Memory website also includes audio and video material, including one of the very earliest movies from 1894.

LAMOLINARA: "One film is simply a motion picture of Edison's assistant [Fred Ott] sneezing. We also have all kinds of audio files, as well. Some of them are from presidents [and] oral histories of former slaves as to what their experiences were during the time of slavery."

Mr. Lamolinara says the American Memory website gets 70-million hits a month from users including serious researchers, students and educators and what they call "lifelong learners" -- people who are just plain curious.

If you're curious, you can surf over to memory.loc.gov, and check it out, or you can get the link from our site, voanews.com/ourworld.

The map of the human genome was completed five years ago. That work has paved the way to new tests to diagnose human illness. Some of the tests, which indicate risk for diseases like cystic fibrosis and some forms of cancer, are part of a growing market for do-it-yourself genetic tests. VOA's Rosanne Skirble has the story.

SKIRBLE: Alison - not her real name - is 32 years old and a magazine editor. She has a baby and is worried about her future. Breast cancer runs in Alison's family. Its most recent victim was her mother.

ALISON: "My cousin had cancer. My aunt had cancer. My grandmother had cancer. All the women on this side of my family have all had breast cancer and all have had it at a young age."

SKIRBLE: Alison suspected she had the gene and was tested at a medical center. She tested positive. Working with a genetic counselor she decided to take a radical step for an otherwise healthy woman and had both of her breasts removed.

ALISON: "I know I made the right choice, and it is a sense of empowerment. I feel like I have control. When women get cancer or men get cancer, cancer controls their life, and I didn't want to wait for it to happen to me. I want to be proactive and get it before it got me."

SKIRBLE: Six months ago a San Francisco-based company called DNA Direct began marketing a home breast cancer test. The company's Chief Executive Officer, Ryan Phelan, says the results don't end up in publicly-accessible medical histories. Rather they are private and controlled by the customer.

PHELAN: "There is a concern that you may be taking a genetic test that shows a predisposition to something like breast cancer. So why should you be flagged by the health care industry as a breast cancer patient? You're not. You are just carrying a risk for breast cancer."

SKIRBLE: Alison - the woman with a family history of breast cancer - agrees that patients should not be discriminated against because they test positive for a certain gene. But she says at-home testing can bypass medical professionals at a critical time.

ALISON: "You are talking about cancer. You are talking about potentially your life here. It was so important to me in my experience to have a nurse who was sympathetic, who I could look in the eye and she could talk to me. When you are getting a response back that you have this genetic mutation, that your possibilities of getting cancer are really high, you need that one-on-one, face-to-face connection."

SKIRBLE: Ryan Phelan of DNA Direct says her company does not leapfrog the medical system. Counselors and doctors are available on-line and on the telephone to discuss detailed customer reports. She says the tests are popular because the results can help customers make decisions that lead to lifestyle changes that can prevent disease.

PHELAN: "And I think that the day is coming where testing is telling us more. What drugs are effective for us, what medications might be most useful, what risk do we need to be most concerned about. And I think that at-home [genetic] testing is the beginning of people beginning to utilize this information to integrate more [fully] their health care, everything from the decisions we make regarding diet and exercise to vitamins to seeing alternative providers for chiropractic care."

LEOPOLD: "Are these people board-certified genetics professionals? Do you have all the information about what you are thinking you are getting tested for? And are you prepared if other information comes back, to deal with that in an open way?"

SKIRBLE: And Bea Leopold adds that it is important to talk with someone who is qualified to interpret the genetic testing results, and who can provide informed advice on decisions that can affect your future health.

CHIMES: By the way, DNA Direct's home genetic tests are not cheap. Most of the tests are several hundred dollars, and one cancer test is over $3,000.

A United Nations report issued this week says progress is being made in the fight against tuberculosis, but that in Africa the campaign against TB is losing ground.

Chris Dye wrote the "Global Tuberculosis Control" report, and he told reporters that TB rates have tripled since 1990 in countries where HIV is a major problem.

DYE: "Continent-wide in Africa, TB incidence - the number of new cases each year - is still going up at three to four percent a year. That is strongly linked to the HIV epidemic. And this African phenomenon is the main reason why TB in the world is continuing to increase."

The WHO says about 1.7 million people died of tuberculosis in 2003, the most recent year with complete statistics.

Also this week, U.S. officials reported progress in fighting another disease. Most people would not consider rubella as big a threat as tuberculosis, but whenever a country wipes out a disease, it's an important public health achievement. And that's just what American officials announced this week, that rubella has now officially been eliminated from the United States. The announcement was made by Dr. Julie Gerberding, head of the government's Centers for Disease Control and Prevention.

GERBERDING: "For the last several years in the United States, we've just had very few cases of rubella, and recently the cases that we do have are not cases that are being transmitted in the United States. They're cases that have been imported from other areas of the world where immunization rates are not as high as they are here in the U.S."

Rubella has been a common and usually not very serious disease among children. But rubella can be disastrous when pregnant women are infected. It can result in birth defects, including blindness and mental retardation.

Cuba was the first country to eliminate the disease about a decade ago, and the United States has been working with other countries in the Americans on controlling rubella. Dr. Mirta Roses, regional director of the Pan American Health Organization, said the control of diseases like rubella has economic and development implications as well.

ROSES: "This is also a very important instrument for poverty reduction in our region -- to keep the equity immunization and to prevent families for having more pain and deaths and disabilities that will impair their possibility of success, of development, of improvement of their condition."

Public health officials in the Western Hemisphere are making progress against the disease, with only about 1,600 rubella cases in the Americas last year. But the picture is bleaker in other developing countries, where the World Health Organization estimates there are 100,000 rubella cases each year.

The Pan American Health Organization is coordinating Vaccination Week in the Americas starting April 23. Health workers will be vaccinating against measles and polio, as well as rubella and other diseases.

Incidentally, rubella was first described in 1814 by medical researchers in Germany, which is why many people still call it "German Measles."

Finally today, Apple's hugely popular iPod portable music player has given a name to the hottest thing in audio -- podcasting. Think of podcasts as radio programs that are distributed over the Internet, and that you listen to on your computer or anywhere on your iPod or similar device. Fans of podcasting say it liberates them from the limitations of radio. VOAs Adam Phillips has more.

PODCAST: The Daily Source Code

PHILLIPS: That's "The Daily Source Code" a podcast produced by the British entrepreneur Adam Curry. Mr. Curry co-wrote "iPodder," the software that allows anyone with a microphone, a computer, an inexpensive audio recording program and access to the Internet to be his own radio producer. Mr. Curry's podcast last August was the world's first, but now there are thousands of podcasts available daily.

A podcaster takes recorded sound -- music or speech or both -- converts it into a digital audio format — usually MP3 — that a personal computer can read. The podcaster then uploads the audio file onto a website. Anyone surfing the Web can download that file and enjoy it anytime, anywhere, on their iPod or another digital player. Users can also subscribe to podcasts, which are then delivered automatically.

This technology has meant an explosion of homemade podcasts all over the internet. Many seem to be made by people who always wanted their own radio show but just happened to lack a radio station. Here is a sample of just a few of them.

PODCAST MONTAGE

At a time when American radio stations, in particular, increasingly sound the same, podcasting has been a boon for folks who enjoy the homespun, personal qualities that local radio once offered. And podcasts can be a source of surprise and delight for enthusiasts like Shea Shackelford.

SHACKELFORD: "I just found this the other night... it was great. I was just listening to all the shows I downloaded that day and all of a sudden next thing I know I'm listening to this guy talking to this woman who runs a coffee shop in his home town.

PODCAST: "Eileen's hands moved almost too fast for me to follow."

PHILLIPS: Podcaster Chris Macdonald of Indiefeed.com says that podcasts are especially appealing to those with unusual tastes and interests.

MacDONALD: "You want to listen to ukuleles [or] sonnets? Someone out there may have that podcast for you."

PHILLIPS: While some podcasts are rather, shall we say, unpolished, others, like this Christian program, have the high production values one associates with mainstream radio.

Mike Bettison, MPR's director of new media, views podcasting as an extension of the internet presence the network already enjoys with so-called "streaming technology."

BETTISON: "Having the iPod certainly allows you to take your media where you want to go. We know that the market penetration for these devices is growing in astonishing ways. It's exciting for me to look for the opportunities where our audience wouldn't necessarily listen to our show if it were on their car stereo, but they would listen to it now because it's available at the gym."

PHILLIPS: Mr. Bettison acknowledges that the interest in podcasting is growing too fast for him to predict where it will lead, yet he seems excited by the prospect of a wonderful ride.

BETTISON: "Actually, when you look at what I would call "hyped [widely touted] technology," this is one of the shortest hype-to-implementation-to-ubiquity cycles I've ever seen!"

PHILLIPS: I'm Adam Phillips in New York.

MUSIC: Our World theme

That's our show for this week. We're always happy to hear from you. Email us at ourworld@voanews.com. Ourworld is all one word. Or write us at -

Our World Voice of America Washington, DC 20237 USA.

Our World is edited by Rob Sivak. Our technical director this week is Gary Spizler. And this is Art Chimes, inviting you to join us online at voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology...in Our World.